13mm vs 20mm Vial Crimper: Differences and How to Choose

The 13 mm and 20 mm in a vial crimper name are the vial's neck-finish size, measured across the outside of the rim, not its volume. A 13 mm crimper closes caps made for 13 mm necks and a 20 mm crimper closes caps made for 20 mm necks, so measure the rim, identify whether the cap is aluminum-plastic flip-off or pure aluminum, and buy the head that matches both. FMFPAX sells a $30 hand crimper, a $189 bench press and a $600 pneumatic crimper, each in 13 mm and 20 mm versions.

13 mm vs 20 mm at a glance

13 mm and 20 mm vial crimping compared
Item 13 mm 20 mm
What the number measures Neck finish: outside diameter of the vial rim (crown) [1][3] Neck finish: outside diameter of the vial rim (crown) [1][3]
ISO 8362-1 standard vials 2R (2 ml) and 4R (4 ml) [2] 6R (6 ml) to 100R (100 ml): 6R, 8R, 10R, 15R, 20R, 25R, 30R, 50R, 100R [2]
Also sold on 5 ml and 10 ml vials with a 13 mm finish [3] 5 ml and 10 ml vials with a 20 mm finish [3]
Stopper and seal Must be the 13 mm size; the vial, stopper and seal share one nominal size [1] Must be the 20 mm size; the vial, stopper and seal share one nominal size [1]
Seal designs (one manufacturer's range) Flip-off, flip-top tear-down, all-aluminum tear-off [1] Flip-off, pull ring, flip-top tear-down, all-aluminum tear-off, all-aluminum tear-down [1]
Seal inner diameter (flip-off, minimum) 13.36 mm [1] 20.22 mm [1]
Vial mouth range listed on FMFPAX QERS machines 12.8–13.0 mm [7][8] 19.5–20.0 mm [7][8]
Crimping head for aluminum-plastic flip-off caps 13A [7][8] 20A [7][8]
Crimping head for pure aluminum caps 13 (QERS-SD; hand crimper "13mm AL"). The QERS-QD is sold with the 13A head only [6][7][8] 20 (QERS-SD, QERS-QD; hand crimper "20mm AL") [6][7][8]
Coarse-neck option None listed 20A (aluminum-plastic) and 20B (pure aluminum) on the FMFPAX hand crimper [6]
Decapper Separate 13 mm decapper tool [4] Separate 20 mm decapper tool [4]
FMFPAX hand crimper / QERS-SD / QERS-QD price $30 / $189 / $600 $30 / $189 / $600 (same price as 13 mm)

Prices as listed on fmfpack.com on 2026-11-03.

What 13 mm and 20 mm mean

A vial seal is sized by the vial neck it closes, not by the volume in the vial. The seal, the stopper and the vial neck share one nominal size, so a 13 mm seal goes on a 13 mm crown and stopper and a 20 mm seal on a 20 mm crown [1].

In the ISO 8362-1 table of injection vials, the 2 ml and 4 ml vials (2R and 4R) have a 13 mm neck finish and every vial from 6 ml (6R) to 100 ml (100R) has a 20 mm neck finish [2]. That is a convention, not a rule: a 5 ml or 10 ml vial can also be made with a 13 mm crimp finish, and the finish is set by the outside diameter of the rim, not by the hole in the vial opening [3]. Two vials of the same volume from different makers can have different necks [1]. Read the neck finish from the vial drawing, or measure the rim.

What changes when you crimp 13 mm instead of 20 mm

1. The head is size-specific

Each FMFPAX crimping head is made for one cap size and one cap construction. The heads are not interchangeable [6][7][8]. You order the version for each size you use. Chromex lists 13 mm and 20 mm crimper jaw sets and manual crimpers as separate part numbers [4].

2. The cap construction changes the head

Aluminum-plastic flip-off caps (plastic top) need the A-series head: 13A, 15A, 20A. All-aluminum tear-off caps need the standard head: 13, 15, 20 [8]. Supplier jaw-set lists show the same split: a 13 mm crimper jaw set, a separate 13 mm flip-off crimper jaw set, and the same pair at 20 mm [4]. Autofits lists the flip-off design as an aluminum-plastic cap (ISO 8362-6) and the tear-off design as an all-aluminum cap (ISO 8362-3) [1].

3. 20 mm has a coarse-neck variation

The FMFPAX hand crimper adds a 20A head (aluminum-plastic cap) and a 20B head (pure aluminum cap) for coarse-neck 20 mm bottles. The listing has no coarse-neck option at 13 mm [6]. Confirm whether your 20 mm bottle has a standard or coarse neck before ordering.

4. Price and machine specs do not change with the size

On the FMFPAX listings the 13 mm and 20 mm versions of each machine have the same price, travel and dimensions [6][7][8]. Pick the size by what you measure on the vial; pick hand, bench or pneumatic by how many vials you close.

How to choose: 6 steps

  1. Find the neck finish. Measure the outside diameter of the vial rim (the crown at the top of the neck) with calipers, or read it from the vial drawing [1][3]. About 13 mm is a 13 mm finish; about 20 mm is a 20 mm finish. FMFPAX lists a measured vial-mouth range of 12.8–13.0 mm for 13 mm and 19.5–20.0 mm for 20 mm [7][8].
  2. Identify the cap. Aluminum-plastic flip-off cap (plastic disc on top) takes an A-series head. All-aluminum tear-off or open-top cap takes the standard head [8].
  3. For 20 mm, check the neck. Standard neck: 20 mm head. Coarse neck: 20A (aluminum-plastic cap) or 20B (pure aluminum cap) on the hand crimper [6].
  4. Pick the drive that matches your volume.
    • Handheld lever crimper, $30 for 8–20 mm heads: no electricity, one cap at a time. Sizes 8, 11, 13, 15, 20, 26, 28, 30 and 32 mm; 26–32 mm heads are $50 [6].
    • QERS-SD bench press, $189: manual press, 130 mm travel, 230 × 230 × 370 mm, 6.5 kg, spring base, limit nut for tightness. Variants 13A, 13, 15A, 15, 20A, 20 [7].
    • QERS-QD pneumatic crimper, $600: foot pedal, 45 kg cylinder thrust, 200 mm travel, 260 × 260 × 480 mm, 11.5 kg, typically 20–40 vials per minute. Needs a customer-supplied compressed air source at 0.4–0.8 MPa (58–116 PSI); the compressor is not included. Variants 13A, 15A, 20A, 20 [8].
  5. Check vial height and base fit (bench machines). The QERS-QD handles vials up to 200 mm tall, from 1 ml to 100 ml [8]. For a custom base hole on either QERS machine, send the vial body diameter (b2) and height (h1) before ordering [7][8].
  6. Crimp a test vial, then set the tightness. A good crimp has smooth sides without creases and a slight depression in the seal center. Adjust between vial or seal lots, because lip and seal thickness vary from lot to lot [5]. Hand crimper: turn the head counterclockwise to tighten, clockwise to loosen [6]. QERS machines: adjust the limit nut [7][8].

FMFPAX vial crimper options

FMFPAX vial crimpers for 13 mm and 20 mm caps
Model Drive 13 mm versions 20 mm versions Price
Manual Vial Crimper, 8–32 mm (MVCC) Handheld lever, no power 13mm PA (aluminum-plastic), 13mm AL (pure aluminum) 20mm PA, 20mm AL, 20A PA coarse neck, 20B AL coarse neck $30 (8–20 mm); $50 (26–32 mm)
Manual Vial Crimper QERS-SD Bench-top manual press, 130 mm travel 13A, 13 20A, 20 $189
Pneumatic Vial Crimper QERS-QD Compressed air 0.4–0.8 MPa, foot pedal 13A 20A, 20 $600

Caps and vials are not included with the hand crimper [6]. See all bottle capping, cap sealing and vial crimping machines, the bottle and vial packaging equipment collection, and pharmaceutical, medical and lab equipment. For where a crimper fits in a small-batch line, read Small-Batch Packaging Line: What to Buy First.

FAQ

Does 13mm or 20mm mean the vial volume?

No. The number is the neck finish: the outside diameter of the vial's crown (rim). Vials of different volumes share a neck finish, and two vials of the same volume can have different necks [1]. In the ISO 8362-1 size table, 2R and 4R vials (2 ml and 4 ml) have a 13 mm neck finish and 6R to 100R vials (6 ml to 100 ml) have a 20 mm neck finish [2], but 5 ml and 10 ml vials are also sold with a 13 mm finish [3]. Measure the rim; do not infer the size from the volume.

Can one crimper seal both 13mm and 20mm caps?

Not with a single head. A crimping head is made for one cap size and construction. On the FMFPAX hand crimper and the QERS-SD and QERS-QD machines, the 13 mm and 20 mm versions are separate heads and the heads are not interchangeable [6][7][8]. Order the head for each cap size you use.

Do flip-off and tear-off caps need different crimper heads?

Yes. Aluminum-plastic flip-off caps need the A-series head (13A, 15A, 20A on the QERS machines). All-aluminum tear-off caps need the standard head (13, 15, 20) [8]. Chromex also lists 13 mm and 20 mm flip-off crimper jaw sets separately from standard jaw sets [4].

How do I adjust the crimp so the cap is tight?

Crimp a test vial and inspect it. A good crimp has smooth cap sides with no creases and a slight depression in the center of the seal [5]. On the FMFPAX hand crimper, turn the head counterclockwise to tighten or clockwise to loosen [6]. On the QERS-SD and QERS-QD, the limit nut sets cap tightness [7][8]. Re-check when you change vial or seal lots, because vial lip and seal thickness vary between lots [5].

Do I need a decapper as well as a crimper?

Only if you remove crimped caps. A decapper is a separate tool, and Chromex lists 13 mm and 20 mm decappers as separate items from the crimpers [4]. A crimper does not open a sealed cap.

Sources

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